Layout work consists of accurately placing marks and lines on a surface in order to guide construction crews when installing building members or performing other work in a construction project. These lines and marks must be accurately placed in order to ensure that the various components of the building fit together properly. If the layout work is not done properly, the construction will not comply with the plans and specifications for the project and expensive remedial work will be necessary.
One of the basic tools for performing layout work is the chalkline, which is a string coated with chalk that will leave a chalk marking on a surface if the string is stretched tautly across the surface and plucked.
New technologically advanced tools have been introduced for layout work, such as electronic and laser leveling instruments, but these tools have not replaced the chalkline because they will not physically mark a surface for the benefit of the construction crew.
In using a chalkline, one person normally holds one end of the string at a specific point (the "base-point") and another person marks off the appropriate length of string, holds the other end of the chalkline, and plucks the string to form the chalk mark. One of these two people is usually a foreman or a supervisor trained in the interpretation of plans, specifications and manufacturers' or supplier's brochures. The other worker is usually untrained and merely clears the path for the chalkline and places and holds the chalkline string at the base-point during the marking process. While the trained foreman or supervisor is reviewing the plans and specifications or checking the dimensions for the layout work, the untrained person usually must wait around with nothing to do, which results in lost labor costs.
Layout work also involves the verification of "plumb" using a "plumb bob." Verifying "plumb" means to verify that a surface or other construction member is truly vertical. In verifying "plumb", a "plumb bob" is suspended from a string that is offset from the surface being checked. The distance of the string from that surface is measured at the top of the string and at the bottom of the string. If both measurements are the same, the surface is said to be "plumb." However, anchoring the "plumb bob" to the surface being checked is sometimes difficult. Therefore, the "plumb bob" line is often nailed or otherwise attached to the surface being checked, thereby leaving marks or damage in that surface.
Layout work sometimes involves using a carpenter's level to verify that markings on a vertical surface are horizontal. However, it is difficult to hold the level against the surface in the proper position and to verify the position of the markings simultaneously. Thus, there is a need for a base-point anchor that can adhere to the vertical surface and help support the level.
Layout work sometimes requires using chalklines or tape rules on ceilings. Thus, there is a need for a base-point anchor that can adhere upside down to a construction member.
Many attempts have been made to provide base-point anchors for chalklines, tape rules and string layout lines, but these all have disadvantages. On wood surfaces, a nail is often used as an anchor. Similarly, on concrete surfaces, a piece of wood is often nailed with concrete nails to the surface and then an additional nail is hammered into the wood. A concrete nail could be nailed directly into the concrete, but this is difficult to do accurately and is quite dangerous in pulling long lengths of string. Still another method employed is to drill a hole at the layout mark, insert a tight fitting nail and use the nail as a base-point anchor. However, this method is inconvenient because of the need to transport an electric drill and cord around the construction site.
All of the preceding methods result in damage to the surface and are time consuming.
It is therefore an object of this invention to provide a base-point anchor that is easily and quickly affixed to the surface of most construction members, horizontal, vertical or upside down, and will not permanently damage or mark the surface.
It is also an object of this invention to provide such a base-point anchor that is very economical, compact and easily transported.
It is a still further object of this invention to provide a base-point anchor that can be mounted on the vertical surface of a wall or other construction member for measuring "plumb."